Human African Trypanosomiasis, HAT (African sleeping sickness) (Kiswahili: “ugojwa wa malale”)

  • This is a zoonotic protozoan infection that is caused by Trypanosoma brucei gambiense, t.b.g (mainly in West Africa) and Trypanosoma brucei rhodesiense, t.b.r (mainly in East Africa).
  • These trypanosomes are transmitted to human being by tsetse fly (Glossina genus).
  • In animals, trypanosomes cause an economically devastating disease known as
  • Kenya is among some African countries that have not reported new cases of the disease in the last 10 yrs.
  • Statistics: proportion of HAT caused by b.g globally-98%; proportion of HAT caused by t.b.r globally-2%; new cases of HAT reported in 2014 - 3796 (in comparison with 10,000 in 2009); population estimated to be at risk - 65 million; countries affected by the disease globally - 36 (in Sub-Saharan Africa); the most affected country globally - Democratic Republic of the Congo (DRC) with more than 70% of the reported cases.
  • Trypanosoma cruzi causes the American sleeping sickness or Chagas diseases that occur mainly in South America.
  1. Transmission
  • Life-cycle;

_Tsetse fly bite

_Metacyclic trypomastigotes injected into skin tissue

_Metacyclic trypomastigotes transform into bloodstream trypomastigotes

_Bloodstream trypomastigotes multiply (by binary fission) in the body fluids

_Tsetse fly bite an infected human

_Bloodstream trypomastigotes in the midgut transform into procyclic trypomastigotes and multiply (by binary fission)

­_The procyclic trypomastigotes transform into epimastigotes that migrate to the salivary gland.

­_The epimastigotes transform into procyclic trypomastigotes

  • Hemolyphatic effects;


_Joint and muscle pain



_Generalized lymphadenopathy

_Facial swelling


_Enlarged lymph nodes in the posterior cervical triangle that is also known as Winterbottom sign (most with t.b.g)

  • Cuteneous effects;


_Typanosomal chancre (mainly with t.b.r)

  • Central Nervous System effects;

(These effects are more fulminant in  t.b.r than in t.b.g)

_Feeling sleepy during the day

_Lack of concentration

_Continous headache





  • Microscopy for trypanosomes (in blood, spinal and other body specimen)





No CNS involvement  for t.b.g

4 mg/kg IM or IV OD x 7-10 days


No CNS involvement  for t.b.r

100mg IV STAT then 20 mg / kg (max. 1g) IV on days 1, 3, 7, 14, and 21


With or without involvement CNS involvement  for t.b.g

100 mg/kg IV QID x 2/52


CNS involvement  for t.b.r

For t.b.g: 2.2 mg/kg IV OD for 10/7.

For t.b.r: 2- 3.6 mg/kg IV OD x 3/7; after 7 days, 3.6 mg/kg OD x 3/7, followed 7 days later by another 3-day course

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